Scale the TiFlash Cluster

This document describes how to scale in and out nodes in the TiFlash cluster.

Scale out a TiFlash node

The following example shows how to scale out a TiFlash node if you deploy TiFlash on the 192.168.1.1 node.

1. Edit the inventory.ini file to add the TiFlash node information:

   Currently, you can only add IP but not domain name.

   [tiflash_servers]
   192.168.1.1
   

2. Edit the hosts.ini file to add the node information:

   [servers]
   192.168.1.1
   [all:vars]
   username = tidb
   ntp_server = pool.ntp.org
   

3. Initialize the new node:

   • Configure the SSH mutual trust and sudo rules on the Control Machine:

     ansible-playbook -i hosts.ini create_users.yml -l 192.168.1.1 -u root -k
     

   • Install the NTP service on the target machine:

     ansible-playbook -i hosts.ini deploy_ntp.yml -u tidb -b
     

   • Initialize the node on the target machine:

     ansible-playbook bootstrap.yml -l 192.168.1.1
     

4. Deploy the new node:

   ansible-playbook deploy.yml -l 192.168.1.1
   

5. Start the new node:

   ansible-playbook start.yml -l 192.168.1.1
   

6. Update the configuration of Prometheus and restart it:

   ansible-playbook rolling_update_monitor.yml --tags=prometheus
   

7. Access the monitoring platform using your browser, and view the status of the cluster and the new node.

Scale in a TiFlash node

The following example shows how to scale in a TiFlash node if you stop the TiFlash service on the 192.168.1.1 node.

1. Take down the node to be scaled in. See Take a TiFlash node down for details.

2. Check whether the node has been offline successfully using Grafana or pd-ctl (the offline process takes some time).

3. After the store corresponding to TiFlash disappears, or the state_name becomes Tombstone, execute the following command to shutdown the TiFlash process:

   ansible-playbook stop.yml -l 192.168.1.1
   

   If the node still has other services and you want to stop TiFlash only, use the following command:

   ansible-playbook stop.yml -t tiflash -l 192.168.1.1
   

4. Edit the inventory.ini and hosts.ini files to remove the node information.

5. Update the configuration of Prometheus and restart it:

   ansible-playbook rolling_update_monitor.yml --tags=prometheus
   

6. Access the monitoring platform using your browser, and view the status of the cluster.